Self-adjusting trimming attachment for sewing machines



Dec. 13, 1932. J. N STEIN 1,891,029

' SELF ADJUSTING TRIMMING ATTACHMENT FOR SEWING MACHINES Filed Sept. 17,1951 l nvenTor. 3 33 Joseph NSTein bydflm [M @LMM Patented Dec. 13, 1932UNITED- STATES JOSEPH N. STEIN, 0F DORCHESTER, MASSACHUSETTSSELF-ADJUSTING TRIMMING ATTACHMENT FOR SEWING MACHINES Application filedSeptember 17, 1931. Serial No. 563,258.

This invention relates-to sewing machine attachments and morepartlcularly to devices for trimming surplus material from the edge ofthe work being sewed.

When performing a trimming operation upon a sewing machinesimultaneously with the formation of a seam, it is essential that thetrimming mechanism function smoothly and accurately in conjunction withthe stitch-forming mechanism. In performing a trimming operation oncertain parts of a shoe upper such, for instance, as the uppermost edgewhere the lining is sewed to the top edge of the upper, the seam must bemade very close to the edge. To accomplish a neat trimming operation insuch case the mechanism must be maintained in accurate adjustment. A.further necessity for maintaining accurate adjustment of the parts isdue to the fact that the needle moves in close proximity to the cuttingedge of the trimming device. If one or more ofthe elements should becomeloosened or should sustain suiiicient wear to cause maladjustment, agreat deal of damage and much loss of time may result. It is the generalobject of the presentinvention to provide a trimming mechanism forasewing machine, the cutting edge of which will be maintainedautomatically in adjusting position with relation to the path of theneedle.

A further object of the invention is to'provide a trimming mechanism inwhich the cutting blade is maintained resiliently in contact with ashoulder upon a rigidly fixed needle plate secured to the work support.

A further object of the invention is to provide a trimming device. thecutting edge of which will assume automatically its proper positionafter it has been reground or after the shape of the blade has beenmodified by any other agency, such as that of the natural wear caused bycontinuous operation of the machine. i

Other objects and features will more fully appear from the followingdescription in connection with the accompanyingdrawing, and will bepointed out particularly in the claims.

In the drawing:

Fig. 1 is a planview oi the end portion of upper of a shoe.

mounted a casing 2.

the work supporting arm of a sewing ma chine showing the trimmingmechanism. 7

Flg. 2 IS a fIOIlt'QleVittlOIl of the parts shown in Fig. 1 illustratingthe work, the

needle plate and a portion of the work support in cross section. I

Fig. 3 is a detail perspective view of the cutting blade showing itsrelation to the work. i

Fig. 4 is a cross section on line 4:'4: Fig. 1.

The invention may be applied readily to sewing machines in general. Asone example of a machine to which the invention is particularlyadaptable, a shoe stitching machine will be described and'illustratedherein. The

machine illustrated is designed for performing certain stitchingoperations upon the i One of such operations is that of forming theseam-at the upper edge of the shoe upper which unites the upper and thelining. The present invention provides the means for trimming thesurplus lining material during the formation of such a seam. Only thoseparts of the machine will be illustrated which are related directly tothe invention. The remaining elements of the machine are or may be'ofstandard design well known to those skilled in the art. Thetrimmingmechanism is mounted desirably upon a frame or work supportingarm 1 ofa sewing machine upon the edge of which is adapted to receivethe usual shuttle mechanism which cooperates with the needle to form thestitch. At the upper portion of the casing 2 ofa work supporting plate3is secured by means of thescrews 4. The outer end of the plate 3 isrecessed to receive a needle plate 5 which is secured in position bymeans of the screws 6. The needle plate is provided with an-aperture 7through which the needle 8 passes during its vertical reciprocation. Theneedle plate 5 iscut away at itsouter edge to form a slot 9 in which afeed dog 10 is received which is actuated by the usual mechanism notshown herein. Situated above the feed dog is a rotary presser foot 11which cooperates with the feed dog to feed the work 12 through themachine. a j i The trimming mechanism is mounted upon a flat plate orboss disposed in a horizontal position at the top of the work supportingarm 1. This flat plate may be integral with or detachably secured to thearm 1. The trimming cutter is composed of a shank portion 13 and acutting blade 14 which are mounted to oscillate in a horizontal plane.Any suitable means may be provided to pivot the cutter. As shown hereinthe cutter is provided with a disk 16 secured to the shank 13 andextending downwardly into a circular recess 17 in a bearing plate 18.

The lower face 19 of the shank 13 rides upon the upper face of thebearing plate 18. The disk 16 secured to the cutter is retained in therecess 17 by means of the plates 20 secured to the upper face of theplate 18 and overlapping the upper face of the disk 16 which is flushwith the upper face of the plate 18. The cutter is thus confined to adefinite horizontal path and receives its oscillations from a drivenelement on the machine. The driving elementmay be a cam situatedwithinthe arm 1 but not shown in the drawings which actuates a follower 21depending downwardly from the shank 13 and extend ing through anaperture 22 in the arm 1.

The shank 13 is composed of two elements, the upper element 23 of whichis pivoted upon a stud 24 secured in the lower portion 25 of the shank.The stud 24 desirably is fixed at the aXis about which the cutteroscillates. The upper member 23 overlies the lower member and isextended beyond the lower member of the shank at the end remote from thestitching point to form a. handle 26. This remote end of the member 23is resilient and is provided with a slot 27. A pin 28 is secured in thelower portion of the shank 25 and normally extends into the slot 27 thuslocking the upper portion 23 and the lower portion 25 against relativemovement. WVhen the work 12 is inserted in the machine, it is desirablethat the knife 14 be swung out of itsoperating position into the dottedline pos1t1on shown in Fig. 1. This is accomplished by raising theresilient portion of the member 23 by means of the handle 26 until thepin 28 clears the slot. The member 23 may then be swung about its pivotpoint upon tne stud 24. When the workis in position the cutter is thenswung back to its full line position with the pin extending into theslot 27.

The knife 14 is carried theupper menrher 23 of the shank 13 in anovelmanner. The end of the knife extending toward the axis of thecutter is provided with slots 29 extending longitudinally thereof a dwithin which are received he screws 30. The screws 30 are securedrigidly to the upper meml'er 23 of the shank 13 by means of screw-threaded end portions. The screws30 are provided with cylindr cal portions 31which accurately fit the slots 29 and permit the knife 14 to movelongitudinally toward and from the axis of the cutter. The heads of thescrews 30 engage the upper face of the knife 14 acting to retain theknife in its proper horizontal plane. Any other suitable means may beprovided for guiding the knife 14 relatively to the member 23. The knife1 1 is provided at its outer end with a downwardly extending verticalportion 32. The forward edge of the portion 32 is sharpened to present acutting edge. The cutting edge is inclined desirably rearwardly from itslower extremity upward- 1y. In forming the inclined cutting edge 33 aportion of the downwardly extending section of the knife 32 is cut awaywhich results in forming a V-shaped recess with the edge 3t of thehorizontal portion of the knife.

The knife 14 is forced outwardly away from the axis of the cutter by anysuitable spring means such, for instance, as the expansion spring 35which is anchored at one end to the stud 24- and is secured at its otherend in an aperture 36 in the blade 14.. The plate 18 is secured to theflat plate or boss upon the work supporting arm 1 by means of aplurality of screws 37 in such position that the vertical end portion 32of the blade 14 will bear with resilient pressure against a verticalface 38 upon the needle plate 5. The outer face of the portion 32 of theknife s formed desirably substantially cylinclrically with respect tothe axis of the cutter thereby permitting the knife to move smoothlyacross the face 38 of the needle plate as the cutter oscillates. Theupper portion of the cutting edge 33 is positioned to engage the work asit is fed across the needle plate.

To illustrate the operation of the device a composite portion of a shoeupper will be taken as an example of the work done by the machine. Thework 12 is composed of an outer layer 39 and an inner layer or lining 40which. are placed between the feed doc; 10 and the presser foot 11 withthe edge of the outer member 39 bearing against the outer face of thedepending portion 32 of the knife. The lining 40 which is invariably outonly roughly to its final shape will project beyond the edge of theouter portion 39 and into the path of the cutting edge 33. The machinethen is started and as the stitching progresses the kn fe 14 isoscillated at high speed and trims the uneven edge of the lining 4Oflush with the edge of the outer member 39.

The distance between the cutting point of the trimming mechanism and thepath of the needle will always remain unchanged since the spring 35 actscontinuously to force the face of the depending portion 32 of the knifeagainst the face 38 of the needle p ate 5. If the knife is removed forsharpening and a slight portion of the blade is removed. the spring 35will act automatically when the blade is replaced in position to restorethe cuttine edge to its original position. If the cutter becomes wornthroughout a long period of operation, it will be forced automaticallyagainst the face 38 by the spring 35, thereby maintaining the accurateposition of the cutting edge. Furthermore, since the needle plate isfixed rigidly in position and of itself positively maintains the cutterin a given position, the needle point cannot be broken by misalignmentwith the aperture through which it operates, nor can it accidentallyengage the cutter. The invention, therefore, provides a highly efficientcutting means which may be maintained indefinitely in perfect runningorder with a minimum of expense and loss of time.

Having thus described the invention, what is claimed as new, and desiredto be secured by Letters Patent, is:

1. A sewing machine attachment for trimming work during the stitchingoperation comprising a power driven pivoted cutter having a shank, aknife blade slidably mounted thereon and movable toward and from thepivot point, a work support, a needle plate fixed thereto presenting avertical stop shoulder, a vertical face upon the end of said knife andresilient means acting to maintain the vertical face of said knife bladein engagement with said stop shoulder.

2. A sewing machine attachment for trimming the work during thestitching operation comprising a power driven cutter pivot-ally mountedto oscillate in a substantially horizontal plane and having a shank, aknife blade carried upon said shank and relatively movable toward andfrom the pivot point having a downwardly extending vertical end portion,a cutting edge flush with the outer face of said vertical endportion, awork support, a needle plate secured thereto presenting a vertical stopshoulder and spring means acting to maintain the end portion of tiheblade in engagement with said stop shoul- In testimony whereof, I havesigned my name to this specification.

JOSEPH N. STEIN.

